Adjustable condenser



06L 1, 1929. BROKAW 1,729,704

ADJUSTABLE CONDENSER Filed Dec. 10, 1927 Inventor; Charles ABPOKEW,

5 Attor'neg.

Patented Oct. 1, 1929 UNITED STATES PATENT OFFICE CHARLES A. BROKAW, F SCOTIA, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY A CORPORATION OF NEW YORK ADJUSTABLE CONDENSER Application filed December 10, 1927. Serial No. 239,055.

My invention relates to electric condensers. More-particularly it relates to variable condensers of the type especially adapted for use in connection with radio apparatus.

Among the objects of my invention is to provide an adjustable condenser of simple construction, camparatively cheap to manufacture and rugged in construction. Another objectflis to provide a condenser of the above character with adjusting meanswhich is effectively locked against displacement.

The invention and all of is features will be more fully understood from the following specification and claims, reference being had to the accompanying-drawing in which Fig. 1 shows a condenser, comprising the feature of my invention, mounted on a suitable base late. In this figure the panel is shown roken, indicating that a series of such con densers may be mounted on the same paneli Fig. 2 is a section through the condenser of Fig. 1. Fig. 3 shows the permanent conductor element of the condenser in position on the base in plan view. Fig. 4 shows the condenser ofthe invention in one positionof adjustment. Fig. 5 shows the condenser of'the invention in another position of adjustment.

Referring more in detail to the drawing, it will be seen that the condenser comprises two 80 metal elements 2 and 3 suitablyv secured to an insulating base 4 and separated from each other by an interposed strip of insulating material 6. The metal element 3 is provided with a terminal 7 to which any suitable wire $5 ma be connected and soldered if desired.

ThlS terminal 7 in the process of assembling the condenser is inserted in the hole 8 of the base plate 4. The metal just above the terminal 7 is bent twice as indicated in Fig. 2, the

length of the leg 9 being preferably substantially equal to the thickness of the plate 4 so that when the upper portion of the plate 'is forced against the upper surface of the base 4 the elbow section 10 looks against the 4 under side of the plate 4. The width of the leg 9, as clearly shown in Fig. 3 is about equal to the diameter of the hole 8. Therefore, the leg 9 is effectively held in a definite position in the hole 8. The opposite end of the plate 3 is provided with a. projecting finger element 11 which projects through a second hole 12, the under side of which is bent to engage the side of the plate 4, thus effectively locking the plate 3 in position.

The interposed insulating element 6 together with the plate 2 are riveted at one end to the base 4 by means of the rivet 13, as clearly shown in Fig. 2. The element 2 is provided with a tail extension 14 which projects through a slot in the base plate 4 and extends below the plate 4. This terminal 14 maybe used for connecting a wire with the element 2. At the opposite end of the device in Fig.

2 there is provided a metal bushing 15 which is embedded in the plate 4. This bushing is threaded and is adapted to receive a screw 16. Referring to Fig. 1, it will be seen that a free end of the element 2 is provided with a ridge 17 on the upper side thereof. Interposed between the element 2 and the head of the screw 16 I provide a washer 18 which is grooved on the under side for the purpose of engaging the ridge 17. The upper side of the washer is countersunkto receive the head of the screw 16. Obviously, therefore, with the construction shown in the drawing and particularly in Fig. 2 it is possible to very carefully and delicately adjust the condenser element 2 with respect to the plate 3 by turning the head of the screw 16. Two extreme positions of the adjustment of the element 2 are shown in Figs. 4 and 5. In Fig 2 an intermediate position of adjustment is shown. I When the plate 2 has been adjusted to the point desired it is then convenient to lock th head of the screw 16 with respect to the wash-- er 18. This may be done in a number of ways as, for example, by sweating the screw 16 to the washer 18 or by dropping heatedwax into the de rcssion of the washer 18 about the head 0 the screw. In this manner the washerand screwma be effectively anchored to each other. 0 viously'after this anchoring operation has been com leted the plate 2 may still be adjusted by epressing the plate 2 so as to cause the groove in the washer 18 to disengage the ridge 17. After this is done the screw 16 may be, rotated carrying with it, of course, the washer 18. Obviouslythe adjustment necessarily involves a rotation of the screw through 180 degrees in order to bring the screw and ridge in juxtaposition agai With a condenser of this construction the plate 2 can be brought nearer and nearer to the plate 3 by turning. the screw 16. If adjustment begins when the condenser is in the position shown in Fig. 4 then by continuing the rotation'of the screw a heel 19 of the plate 2 will first strike the insulation 6 at the right, as shown in Fig 2. As the rotation of the screw is continued the space between the plate 2 and the insulation 6 continues to grow smaller until the plate 2 finally assumes the position shown in Fig. 5. In this position the plate 2, if properly formed, is in contact with the insulation plate 6 all along the face of the plate 2 between the hole 8 and the heel It will be understood that while Ihave illustrated my invention in connection with a specific formof device, I do not wish to be limited to the specific construction shown inasmuch as in view of the disclosure modifica tions may be made without departing fromthe spirit of the invention or the scope of the claims contained herein.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In an electric condenser, in combination, an insulating base, a metal condenser element disposed along the face of the said base with the ends thereof extending through perforations in said base and bent to lock said element to said base, a strip of insulation extending over said element and a second metal" condenser element located over said strip, said insulation and said second plate being secured to said base, means in said base for receiving a screw," said screw projecting through an opening in said second condenser element, a washer interposed between the head of the screw and the second condenser element, whereby the said second element may be adjusted, and means for locking the washer against rotation with respect to said second element.

2. In an electric condenser, in combina tion, an insulating base, a metal condenser element disposed along the face of the said base with the ends thereof extending through perforations in said base and bent to lock said element to said base, a strip of insulation extending over said element and a second metal element located over said strip, said insulationand said second element being secured to said base, means in said base for recelving a screw, said screw projecting through an opening in said second condenser element, a washer interposed between the head of the screw and the second condenser element whereby said second element may be adjusted, means for locking the washer against rotation with respect to said second element, said means comprising tongue and.

groove elements, one of said tongue and groove elements being located on the second condenser element and the other on the washer.

supporting the condenser, a pair of metal condenser elements insulated from each other and located on said base, means for moving one of said metal elements with respect to the other whereby the capacity of the condenser may be adjusted, said means comprising ascrew in threaded engagement with said base, said screw extending through one of said metal elements and being in interlocked engagement therewith with respect to the longitudinal movement of the screw whereby the interlocked metal element may be moved toward or away from the other metal element when the screw is rotated, and means for locking the screw against rotation, said means comprising tongue and groove elements in interlocked engagement, one of said elements being located onthe movable metal element.

5. In an adjustable condenser, a base for supporting the condenser, a pair of metal condenser elements insulated from each other and located on said base, means for moving one of said metal elements with respect to the other whereby the capacity of the condenser may be adjusted, said means comprising a screw in threaded engagement,

with said base, said screw extending through one of said metal elements and being in interlocked engagement therewith with respect to the longitudinal movement of the screw whereby the interlocked metal element may be moved toward or away from the other metal element when the screw is rotated, a collar about said screw, and means for locking the screw against rotation, said means comprising tongue and groove ele ments in interlocked engagement, one of said elements being located on the movable metal element, and the other being located on said collar, said collar being secured to said screw against rotation thereon.

6. In an adjustable condenser, in combination, a base, a metal condenser element disposed along the face of said base, a strip of insulating material extending over said metal element, a second metal condenser elecured to said base in permanent relation thereto, said second metal element having one end thereof secured to said base with the other end thereof free to be moved toward and from the first metal element, a screw extending through said second metal element with the head thereof on one side of the second metal element and with the threads thereof in operative engagement with said base on the other side of the metal element whereby the second metal element may be adjusted with respect to the first metal element to vary the capacity of the condenser by turning said screw, and means for locking the head of the screw to the second metal element to prevent rotation of the screw.

In witness whereof, I have hereunto set my hand this 8th day of December, 1927.

. CHARLES A. BROK-AW. 

